resources management

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CRITICAL PATH METHOD 3

KAEA 4165Construction Management and Technology

Dr. Tan Chee Ghuan

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Resource Management

• The most important resources: people, machines,

materials and money.

• If these resources are available in abundance, then the

project could be accelerated to achieve shorter projectduration.

• If these resources are severely limited, then the result

more likely will be a delay in the project completion

time.

• In general, from a scheduling perspective, projects

can be classified as either time constrained  or

resource constrained.2

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Resource Leveling

• Time constrained project - project completion time cannot be delayed even if additional resources are required.

However, the additional  resource usage  should be no

more than what is absolutely necessary. 

•The primary focus purposes of scheduling in timeconstrained projects is to improve resource utilization.

This process is called resource leveling. 

• It applies when it is desired to reduce the hiring and firing

of resources and to smooth the fluctuation  in the dailydemand of a resource.

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Resource Leveling

• In this case, resources are not limited and project duration

is not allowed to be delayed.

• The objective in this case is to shift non-critical activities

of the original schedule, within their float times so that a

better resource profile is achieved.

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Resource Scheduling

• Resource constrained project  - the level ofresource availability cannot be exceeded.

• In those situations where resources are

inadequate, project delay is acceptable, but the

delay should be minimal.

• The focus of scheduling in these situations is to

prioritize and allocate resources in such a manner

that there is minimal project delay.• However, it is also important to ensure that the

resource limit is not exceeded and the technical

relationships in the project network are respected.5

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Resource Scheduling

6

Shortage of resources is a major challenge for construction projects. i.e.

number of skilled labor is limited, a related equipment has to be returned

as soon as possible, a limited require our special consideration.Scheduling under these resource constraints becomes a complex

problem, particularly when more than one resource is limited.

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Resource Scheduling

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Example 1: Resource Leveling

Critical path:A-C-F-H-K

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Critical path:A-C-F-H-K

Example 1: Resource Leveling

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Activity  Duration  Total Float/Slack   Resource HoursNeeded Per Week  

Total Resources Required 

A  5  0  6  30 

B  4  1  2  8 

C  5  0  4  20 

D  6  3  3  18 

E  6  1  3  18 

F  6  0  2  12 

G  4  3  4  16 

H  7  0  3  21 

I  5  3  4  20 

J  3  5  2  6 

K   5  0  5  25 Total  194 

Example 1: Resource Leveling

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Example 1: Resource Leveling

• On day 10 the required resource hours is 10

• If project is budgetted for up to 10 resource units per day, then it is

acceptable.

Day 10

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Example 1: Resource Leveling

• How if the project is limit to 9 resources hour?

•  Activity C, D, and E are all scheduled on this day and have require 4, 3, and

3 hours respectively.

6 

2

4

3 

4 

4 

2 

3 

3 

2 

5 

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Which activity should be adjusted?

• C is on the critical path

• E has 1 day slack

• D has 3 days of slack (we can split the activity)

Example 1: Resource Leveling

6 

2

4

3 

2 

3 

3 

4 

3 

Critical path:A-C-F-H-K

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Example 2: Resource LevelingQuestion:

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Solution:

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 Activity M has a free float of 7 weeks.

Shifting activity M by 7 weeks will reduce

the peak usage of the resource on weeks

10 and 11 and increase the usage onweeks 17 and 18. Also, shifting activity M

will give chance for preceding activities to

be shifted.

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 Activity J can be shifted by 6, however it

has 8 weeks free float. By shifting activity

J, the free float of both activities E and F

are changed.

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Shift activity L by 2 weeks to optimize the

resource usage. The free float of activity

will be changed to 2 weeks.

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• Next, shift activity E by 10 weeks to

improve the resource usage.

• Shift activity H by 2 weeks.

• Finally, shift activity F by 1 week.

Resource histogram after leveling

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Question:

• Resource limit is set at 8 hourly units per day. Display the

amount of resources required as a function of time.

 A

B D E

CF

Example 3: Resource Scheduling

Activity Resource Duration ES Slack LF

 A 6 4 0 0 4B 2 1 4 0 5

C 2 3 4 4 11

D 7 4 5 0 9

E 3 2 9 0 11

F 6 1 11 0 12

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 A

B D E

C F

Activity Resource Duration ES Slack LF

 A 6 4 0 0 4

B 2 1 4 0 5

C 2 3 4 4 11

D 7 4 5 0 9

E 3 2 9 0 11

F 6 1 11 0 12

Project delay 2

days due to

resource limitation

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Rearrange activities

within their slack tocreate a more level

profile. Splitting C

creates a more level

project.

Project delay 2days due to

resource limitation

E l 4 R S h d li

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Example 4: Resource SchedulingQuestion:• A construction project is presented using an AOA as shown with the

duration and number of workers required to complete each activity.Determine the critical path and the project duration. If only 11workers are available for this project, workout the minimum durationrequired  to complete the project using the serial method forallocating the workers. Make use of the table below.

1

4

2 5

7

3

8

6

2

6

3

5

4

5

3

4

4

5

4

6

4

6

4

4

workers

weeks

Solution:

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Solution:

1

4

2 5

7

3

8

6

2 34

3

4

4

4

40 2

2 6

6 10

2 6

6 9

0 3

3 7

7 11

ET EF

LS LF

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Priority Rules:

1. Critical Paths (zero

float)

2. Earliest Start

3. Least Float

4. Largest No. of

Resource - week

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Priority Rules:

1. Critical Paths (zero float)

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Priority Rules:

1. Critical Paths (zero float)

2. Earliest Start

3. Least Float

4. Largest No. of Resource

- week

CHECK DEPENDENCY PATH!!

Example 5 Resource Scheduling

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Example 5: Resource SchedulingQuestion:• Resource M limited to 5, resource L limited to 8.

•  Calculate the activity times and identify the critical path.

• Produce a scheduled start date for each activity based on the resourcesloading diagrams for both M and L which do not exceed the resourceslimitations. Use the priority sorting of early start  –  total float  inpreparing the resource loading diagrams

Activity Duration

(Weeks)

Resource requirement

M L

A 8 2 2

B 7 4 2

C 6 3 2

D 8 4 2

E 6 4 -

F 8 - 5

G 6 3 -

H 7 - 4

I 9 4 -

J 3 - 4

E l 5 R S h d li

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Example 5: Resource Scheduling

Given:

A

C

B D

E G

I

F

H

J